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Biomedical subjects

I Lalezari

Publications and source records attributed to I Lalezari.

At least 19 recordsLinked to original sources
PubMed2000

Novel inhibitors of advanced glycation endproducts (part II).

Enhanced formation and accumulation of advanced glycation endproducts (AGEs), have been implicated as a major pathogenesis process leading to diabetic complications, normal aging, atherosclerosis, and Alzheimer's Disease. Several potential drug candidates as AGE inhibitors have been reported recently. The aim of this study was to develop classes of novel inhibitors of glycation, AGE formation, and AGE-crosslinking and to investigate their effects through in vitro chemical and immunochemical assays. A total of 92 compounds were designed and synthesized. The first 63 compounds were reported before. Nearly half of the 29 novel inhibitors reported here are benzoic acid derivatives and related molecules, and found to be potent inhibitors of multistage glycation, AGE formation, and AGE-protein crosslinking. All 29 compounds show some degrees of inhibitory activities as detected by the four assay methods, 9 compounds demonstrated high percent inhibition (PI) in all tests, 30 to 40 times stronger than aminoguanidine.

Animals↗
PubMed1999

Novel inhibitors of advanced glycation endproducts.

Enhanced formation and accumulation of advanced glycation endproducts (AGE's) have been proposed to play a major role in the pathogenesis of diabetic complications, aging, atherosclerosis, and Alzheimer disease leading to progressive and irreversible intermolecular protein crosslinkings. This process is accelerated in diabetes and has been postulated to contribute to the development of a range of diabetic complications including nephropathy, retinopathy and neuropathy. Several potential drug candidates as AGE inhibitors have been reported recently. Aminoguanidine is the first drug extensively studied both in vitro and in vivo. We have developed a new class of compounds as potent inhibitors of glycation and AGE formation. The novel inhibitors reported here are aryl (and heterocyclic) ureido, and aryl (and heterocyclic) carboxamido phenoxy isobutyric acids and related molecules, which were found by in vitro assay methods to be potent inhibitors of multiple stage of glycation and AGE formation.

Animals↗
PubMed1995

Evaluation of 2-(3-aminobenzamido)-2-deoxy-D-glucose as a radiosensitizer.

PURPOSE: 3-Aminobenzamide (3-AB), an inhibitor of poly(adenosine diphosphate [ADP]-ribose) synthetase, functions as a radiosensitizer in several human tumor cell lines. 2-(3-AB)-2-deoxy-D-glucose (3-AB-G) was designed to increase preferentially the intracellular concentration of the drug in tumor cells. Both the toxicity and effectiveness of 3-AB-G as a radiosensitizer were determined. MATERIALS AND METHODS: The toxicity of 3-AB-G was measured in HeLa and Chinese hamster ovary cells. The radiosensitizing effect of 3-AB-G was determined for both cell lines. RESULTS: 3-AB-G was not toxic to cells at concentrations of 10 mmol/L or less. 3-AB-G did not alter cell survival after irradiation. CONCLUSION: 3-AB-G was not an effective radiosensitizer for the cells tested. Coupling 2-deoxyglucose to 3-AB may block the uptake of the inhibitor into the cell by altering the ability of the receptor to recognize the molecule or may interfere with the specificity of the inhibitor for poly(ADP-ribose) synthetase.

Animals↗
PubMed1992

Excision of sugar-phosphate products at apurinic/apyrimidinic sites by DNA deoxyribophosphodiesterase of Escherichia coli.

It has been shown previously that the DNA deoxyribophosphodiesterase (dRpase) activity of Escherichia coli excises 2-deoxyribose 5-phosphate moieties at apurinic/apyrimidinic (AP) sites in DNA following cleavage of the DNA at the AP site by an AP endonuclease such as endonuclease IV of E coli. A second class of enzymes that cleave DNA at AP sites by a beta-elimination mechanism, AP lyases, leave a different sugar-phosphate product remaining at the AP site, which has been identified as the compound trans-4-hydroxy-2-pentenal 5-phosphate. It is shown that dRpase removes this unsaturated sugar-phosphate group following cleavage of a poly(dA-dT) substrate containing AP sites by the action of the AP lyase endonuclease III of E. coli. The Km for the removal of trans-4-hydroxy-2-pentenal 5-phosphate is 0.06 microM; the Km for the removal of 2-deoxyribose 5-phosphate is 0.17 microM. It was verified that the sugar-phosphate product removed by dRpase from the endonuclease III-cleaved substrate was trans-4-hydroxy-2-pentenal 5-phosphate by conversion of the product to the compound cyclopentane-1,2-dione. The dRpase activity is unique in its ability to remove sugar-phosphate products after cleavage by both AP endonucleases and AP lyases.

DNA, Bacterial↗
PubMed1990

New effectors of human hemoglobin: structure and function.

We describe the actions of two new allosteric effectors of hemoglobin, 2-[4-(3,5-dichlorophenylureido)phenoxy]-2-methylpropionic acid (L35) and 2-[4-(3,4,5-trichlorophenylureido)phenoxy]-2-methylpropionic acid (L345). Each of them binds to two pairs of symmetry-related sites in the central cavity of human deoxyhemoglobin. One pair of sites overlaps with that occupied by bezafibrate [Perutz et al. (1986) J. Am. Chem. Soc. 108, 1064-1078]. The other sites are new, and the pair occupied by L35 is different from that occupied by L345. All the sites are at least 20 A from the site where organic phosphates are bound. L345 is by far the most potent allosteric effector of hemoglobin ever described. At a concentration of 0.1 mM, it raises the P50 of a suspension of red cells by 50%; at 0.2 mM it raises the P50 2.5-fold. At acid pH, it reduces Hill's coefficient to near unity and prevents complete oxygen saturation even under 1 atm of pure oxygen. In azidemethemoglobin at pH 6, it induces a transition to higher spin. These properties are reminiscent of those of teleost fish hemoglobins that exhibit a Root effect. The influence of L35 and L345 and that of organic phosphates on the oxygen affinity are additive, but they compete with chloride. L35 acts more weakly than L345, but can be made to induce the same effects as L345 alone by adding inositol hexaphosphate. Both compounds increase the alkaline and acid Bohr effects. They alter the bimolecular kinetics of CO recombination after a flash by increasing the slowly reacting fraction of hemoglobin in the T state at the expense of the fast-reacting fraction in the R state.(ABSTRACT TRUNCATED AT 250 WORDS)

Allosteric Regulation↗
PubMed1989

Synthesis and investigation of effects of 2-[4- [[(arylamino)carbonyl]amino]phenoxy]-2-methylpropionic acids on the affinity of hemoglobin for oxygen: structure-activity relationships.

A series of 2-[4-[[[(substituted-phenyl)amino]carbonyl]amino]phenoxy]-2- methylpropionic acids and other substituted phenoxyacetic acids were synthesized and tested for their ability to reduce the affinity of hemoglobin for oxygen. 2-[4-[[[(3,4,5-trichlorophenyl)amino]carbonyl]amino]phenoxy]-2- methylpropionic acid was found to be the most potent compound known. Structure-activity relationships of the compounds synthesized are discussed.

Erythrocytes↗
PubMed1988

Synthesis and antineoplastic activity of 5-aryl-2,3-dihydropyrrolo[2,1-b]thiazole-6,7-dimethanol 6,7-bis(isopropylcarbamates).

A series of 1-thia analogues of the pyrrolizine bis(carbamate) 9 (NSC-278214), namely 5-aryl-2,3-dihydropyrrolo-[2,1-b]thiazole-6,7-dimethanol 6,7-bis(isopropylcarbamates) (7a-d), were prepared by multistep syntheses from the proline analogue thiazolidine-2-carboxylic acid. The compounds were tested for growth inhibitory activity with the HL-60 human promyelocytic leukemia cell line. Three of the compounds had antileukemic activity equal to that of 9, while a 4-chlorophenyl analogue was approximately 75% more potent. A simple aromatic derivative, 1,2-benzenedimethanol 1,2-bis(isopropylcarbamate) (8), had no activity in this system. Antitumor activity was also tested in a colony formation assay with HT-29 human colon carcinoma cells. Compounds 7a-d reduced relative cell survival by over 3 logs at a concentration of 300 microM (2-h exposure), while a comparable inhibition was observed with 150 microM 9. Hence compounds 7a-d retain significant antineoplastic activity.

Carbamates↗
PubMed1988

LR16, a compound with potent effects on the oxygen affinity of hemoglobin, on blood cholesterol, and on low density lipoprotein.

2-[4-(3,4-Dichlorophenylureido)phenoxy]-2-methylpropionic acid, LR16, combines with two symmetrically related sites in the central cavity of deoxyhemoglobin, 20 A away from the binding site of 2,3-bisphosphoglycerate, and acts as an allosteric effector synergistic with 2,3-bisphosphoglycerate. LR16 (1 mM) raises P50, the partial pressure of oxygen needed to achieve half-saturation with oxygen of a hemolysate of human hemoglobin, about 50 times more strongly than 1 mM 2,3-bisphosphoglycerate. Oral administration of LR16 (at small doses that produced no ill effects) to rats that were fed a diet rich in cholesterol caused substantial reductions of total serum cholesterol and low density lipoprotein-cholesterol, while high density lipoprotein-cholesterol remained unchanged.

Animals↗
PubMed1987

Effect of mono- and diaminopyridines on release of [3H]norepinephrine from isolated guinea-pig atrium.

Neurochemical evidence has been obtained that 4-aminopyridine, 3,4-diaminopyridine and 3,3-dimethyl-1-(4-amino-3-pyridyl)urea HBr (LF-14), concentration-dependently enhanced the stimulation-evoked release of [3H]norepinephrine ([3H]NE) from isolated guinea-pig atrium. The effects of aminopyridines, compounds known to inhibit potassium channels, were Ca0-dependent. High pressure liquid chromatography, combined with radiochemical detection, indicated that the increased stimulated release of radioactivity was due to [3H]NE. Since the aminopyridines studied also enhanced the release of [3H]NE from atrium treated with cocaine, a blocker of uptake1, it seems likely that the increased release of NE caused by the aminopyridines is due to the enhanced release of NE from sympathetic axon terminals and not to the inhibition of reuptake. It is probable that the sympathomimetic cardiac effects (positive inotropic and chronotropic effect) of aminopyridines observed in animal experiments is due to the increased release of NE, caused by these compounds.

4-Aminopyridine↗
PubMed1984

Carbohydrate-specific antibodies in normal human sera. I. Characterization of specificity for beta-D-glucose.

A glucose-dependent hemagglutinin, present in the serum of an apparently healthy donor, is shown to be a polyclonal IgM immunoglobulin with specificity for beta-D-glucopyranose configuration. The antibody did not agglutinate erythrocytes coated with hexoses differing from glucose at C2, C3, or C4 positions or lacking the primary alcohol group at C6 position. The hemagglutination reaction, quantitated in a continuous flow system, was inhibited by the addition of 6-deoxyglucose, 5-thioglucose, 2-deoxyglucose, 2-aminoglucose or 3-0 methylglucose. D-glucose, in beta- but not in alpha-configuration, attached by a glycosidic bond to another glucose or to an aglycone, was also inhibitory. A cross-reactivity was demonstrated between glucose and 6-deoxyglucose by antibody absorption and elution techniques. The donor's serum contained independent antibodies that reacted with erythrocytes coated with melibiose, gentiobiose, cellobiose, or N-acetylmannosamine. Further investigation revealed that antibodies are present in sera of all normal adults against erythrocytes coated with melibiose and N-acetylmannosamine and with high frequency against erythrocytes coated with gentiobiose, L-rhamnose, cellobiose, D-mannose, lactose, or D-galactose.

Antibody Specificity↗
PubMed1977

Alkaloids of Glaucium oxylobum Boiss and Buhse, Population Ab-Ali.

Glaucium oxylobum Boiss and Buhse, population Ab-Ali, was demonstrated to contain one major alkaloid, glaucine (0.7%), and two minor alkaloids, O-methylatheroline and predicentrine, in the aerial parts. The root also contains protopine. Glaucine and O-methylatheroline were detected for the first time in this species, and predicentrine was detected for the first time in the Glaucium genus.

Alkaloids↗
PubMed1977

Alkaloids of Glaucium flavum Grantz, populations Isfahan and Kazerun.

Glaucium flavum Grantz, population Isfahan, contained four major alkaloids: dicentrine (0.8%), bulbocapnine (0.42%), protopine (0.35%), and salutaridine (0.2%). G. flavum Grantz, population Kazerun, contained four major alkaloids: dicentrine (1.4%), bulbocapnine (0.5%), O-methylflavinantine (0.5%), and salutaridine (0.3%); it also contained two minor alkaloids, protopine and alpha-allocryptonine. O-Methylflavinantine was found for the first time in the Papaveraceae.

Alkaloids↗
PubMed1977

Alkaloids of Papaver orientale L.

According to the alkaloid profiles, five different chemotypes (A, B, C, D, and E) were classified in Papaver orientale L. with haploid chromosome number n = 14. Chemotype A had only oripavine; chemotype B contained oripavine and thebaine; chemotype C had isothebaine in addition to oripavine; chemotype D contained oripavine and alpinigenine; and chemotype E had oripavine, thebaine, and alpinigenine. In all chemotypes, oripavine was either the sole alkaloid or the single major alkaloid.

Alkaloids↗
PubMed1976

Major alkaloids of Glaucium flavum Grantz, population Ghom.

Glaucium flavum Grantz, population Ghom, contains 1.24% dicentrine, 0.89% bulbocapnine, and 0.05% salutaridine in dry aerial parts and root of the flowering plant. These alkaloids were detected for the first time in the Glaucium genus.

Alkaloids↗